Portable antennae are necessary in many applications. In biotelemetry applications, where the movements of a person is tracked, that person needs to carry a portable antenna to broadcast the signal from the locator transmitter that he or she carries. Those tracking the person also need to carry portable antennae depending on the nature of the application. For example, in a search and rescue biotelemetry application where the person being tracked is lost in the wilderness, there may not be a tracking station with fixed equipment within range for receiving the signal from the locator transmitter carried by the person being tracked. As such, those who are tracking the person need to carry portable antennae with them to get within range. Furthermore, in biotelemetry applications where the person tracking wishes to stay in close proximity to the person being tracked, such as in supervised outings for patients with Alzheimer's, the tracking person needs to carry a portable antenna.
Hand-carrying a portable antenna in many circumstances may prove awkward and impractical. For example, hand-carrying an antenna during a search and rescue operation or when supervising an Alzheimer's patient in an outing will significantly reduce mobility and may prove intrusive as the tracking event will not be discrete Furthermore, in many biotelemetry applications, the frequency range used by the transmitters and receivers is in the ˜100 to ˜300 MHz range. This will make the minimum size of the antennae that are capable of transmitting or receiving signals in the range of ˜0.75 m to ˜0.25 m, which would make their manual transport difficult.
Attempts have been made to make lighter, easier-to-carry antennae for mobile applications. Two such attempts are disclosed in European Patent Application 0 274 592 A1 by Tamura, claiming priority Japanese patent applications 171032/86, 171033/86, 171034/86, 88177/87 and 88178/87, and PCT application WO 01/36728 A1 by Wilson et al. Tamura discloses a light, flexible antenna deposited on film like material, making the structure foldable into a compact size for transportation. While an antenna according to Tamura may be easy to transport, its operation will require antenna to be unfolded. As such, an antenna according to Tamura would be difficult to operate while in motion.
Wilson discloses a textile fabric ribbon into which conductive elements running the length of the ribbon are knitted, woven or braided. The ribbon, which may be releasably attached to an item of clothing, may be used as an antenna. The major disadvantage of this scheme is the difficulty of fabricating an antenna according to Wilson, namely the difficulty of knitting, weaving or braiding a conductor into a textile fabric.
What is required is a portable antenna that can be operated while the carrier of the antenna is in motion and that is simple to fabricate.